

where \(t_j\)  is the tangent to \(S_j.\) 

The relation (REF ) follows immediately from [1]}. Let \(\Omega _i\)  be the angular sector bounded by \(S_{i}\)  and \(S_{i+1}.\)  Let \(W \in \mathcal {B}(\Omega )\)  such that \(\nabla W\in \mathcal {B}(\Omega ,\mathbb {R}^2)\)  with bulk density \(\nabla w = -\sum _{j=0}^{i} \gamma _j \nu _j\)  in \(\Omega _i.\)  We use [1]} to obtain
\(\operatorname{Curl}\operatorname{Curl}(\nabla W\otimes \nabla W)= \sum _{j=1}^{n-1}\sum _{i=0}^{j-1} \gamma _i \gamma _j \langle \nu _i,t_j \rangle \delta _O,\) 
